Made TypeScript Intellisense Writer [try to] extract generic argument from property types that are collections.

While it is technically impossible to extract generic argument from a generic type ref in EnvDTE, this commit uses a heuristic to make it work at least in some simple cases.

In particular:

* First, the type name is parsed out of the ref using the <> characters as markers.
* If it's a known simple type (like string, int, etc.), then that type is used.
* Otherwise, we try to ask the current project's CodeModel for a type with that name, and use that.
* If the code model doesn't return anything - that's it, no more guessing, the type will just end up as "any".